Conventionally, in an image forming apparatus such as a MFP (Multi Function Peripheral), a plurality of cassettes are arranged to store paper, and the paper taken out of the cassette is conveyed to an image forming section through a conveyance path to be formed with an image. Further, the paper formed with an image is discharged through the conveyance path. A paper detection mechanism is arranged on the conveyance path to detect the conveyance of paper.
The paper detection mechanism comprises a lever for detecting the paper and an actuator for driving the lever, wherein the actuator includes a torsion coil spring for energizing the lever towards the conveyance path. If the paper is conveyed on the conveyance path, the lever is pressed by the paper and pivots against the energizing force of the torsion coil spring. Then the conveyance of the paper can be detected by determining the pivoting of the lever.
By the way, in the paper detection mechanism which uses the torsion coil spring, large load is applied to the paper when the paper collides with the lever. Especially, when thin paper or soft paper is conveyed, there is a drawback that the front end of the paper deforms due to the load when colliding with the lever and paper jam occurs. Further, though the torsion coil spring is arranged nearby the bearing part of the rotation shaft constituting the actuator, the torsion coil spring may slant due to the repulsive force of the spring. If the torsion coil spring slants, part of the spring enters the bearing part, which may lead to a failure that the actuator cannot operate normally.